1. Technical Field
Example embodiments relate generally to image sensors, and more particularly image sensors including a plurality of unit pixel arrays where two pixels share one readout circuit.
2. Description of the Related Art
In general, a complementary-metal-oxide-semiconductor (CMOS) image sensor is a device used in a smart phone or a digital still camera to capture an image and the CMOS image sensor is required to be manufactured in a small size according to the tendency of portable devices manufactured in a small size with a slim structure.
As image sensors have tended toward the miniaturization, a size of a unit pixel area is reduced so that the fill-factor (a ratio of a photodiode area to a unit pixel area) is also reduced.
For this reason, recently, a shared pixel structure allowing two photodiodes to share one readout circuit has been adopted to reduce an area of switch transistors per a unit pixel.
In the shared pixel structure, the minimization for a 1H period is necessary for a high frame rate, but there is limitation in the minimization due to the restriction of pixel charge transmission and A/D conversion time. In order to overcome the above limitation, a 2RSR (2 Row Simultaneously Read) scheme is employed to simultaneously read 2 rows for the 1H period.
However, when the 2RSR scheme is used, if photodiodes having mutually different colors share one column line through one readout circuit, mismatch may occur between colors.